The possibility of developing a (green forage and grain) system, the influence of population densities and fertilization on soybean were studied. A design of divided plots was used (main plots: fertilization and subplots: three population densities l. The soybean can be used as a double purpose plant. A population density of 360000 plants/ha with fertilization gives the best forage yield in dry matter (865.44 kg/ha) and the maximum grain production (1073 kq/ha). This work is considered to be the first done in Colombia using soybean as forage and grain producer under field conditions.